As set forth in a commonly assigned U.S. patent application Ser. No. 719,092 Apr. 2, 1985, entitled "MULTI-FORMAT LASER PRINTER" in the name of Chandler et al, a laser printer is provided which includes means for changing spot size, line scan length and page length to change the image format size while still providing pyramidal corrections.
More specifically, the laser printer in the above-identified U.S. application is shown in FIGS. 1-3. It uses a rotating polygon, at least one movable cylindrical mirror and movable lens for changing the line scan length. A parameter of the cylindrical mirror is adjusted to correct for pyramidal error at the new line scan length.
Although this arrangement provides a significant improvement in the art, it requires that the cylindrical mirror and cylindrical lenses must be moved and accurately positioned. With high speed printing, this presents technical difficulties.